From the perspective of the North or South Pole, every year is essentially one long day that lasts half a year and one long night lasting the other half. This has enormous impact on how much solar energy is received in different times of year, which in turn influences physical processes, such as the freezing and thawing of snow and ice, biological processes, such as migration, and the lives of people who live in polar regions.
If the Earth were perpendicular on its axis, everywhere on the planet would receive an equal amount of sunshine (and darkness) every day. But because of the tilt of the Earth on its axis (currently 23.5 degrees off the perpendicular), only two days a year — the Equinoxes every spring and fall — have equal amounts of sunshine everywhere.
The images below, using NASA Visible Earth images, provide a view from above the North Pole, 90°N 0°W at 12:00 Universal Time on the solstices and equinox.
Solstice- December 21
Equinox- September 21 & March 21
Solstice- June 21
You can create your own images of Earth from nearly any perspective and any time of the year imaginable on the Fourmilab Switzerland website’s Earth Viewer.
What would the view from the South Pole, 90°S, look like? Use the Earth Viewer to see for yourself.
The seasonal clock of the solstices and equinoxes is magnified in Polar Regions. In the northern hemisphere, the September Equinox signals the end of summer melting and the beginning to shorter days, longer nights, which peak on the vernal solstice in December before the nights begin to get shorter, the days longer. At the Spring Equinox in March, the days are longer than the nights, accelerating the seasonal melt.
How does the seasonal clock change physical, biological and social processes and routines in your communities? How might that compare with polar regions?
Here are some resources and activities to examine seasonal change:
Modeling the Reason for Seasonal Change
How Do Seasonal Temperature Patterns Vary Among Different Regions of the World?
A Reason for the Season
Sunrise at the South Pole
Length of Day and the Seasons
Sun Path activity
Windows Around the World
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Wednesday, 05 September 2007 21:39
Solstices, Equinoxes, and the Polar RegionsWritten by Rhian Salmon
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